Relay Race

This challenge is all about communication. From a robot design perspective, there’s a technical challenge about how to make one robot signal another. But beyond that, there’s also a great opportunity for students to develop their teamwork and communication skills. If, like me, you have normally have students working in groups of two or three with a single robotics kit, this challenge forces students to work together in pairs of teams, with each team responsible for one of the robots.

Relay Race – Initial Setup

The challenge

Program a pair of robots to run a relay race.

The details:

  • Each side of the relay race track will be marked by a line of tape, about 2 metres apart.
  • This challenge requires two robots – you may need to pair up with another team.
  • One robot from each pair will start lined up on one side of the track (marked with tape), with the other robot from each pair lined up on the other side.
  • On “Go!”, the first drives forward.
  • When it reaches the other side of the track, the second robot starts and drives back to the first side.
  • The first one back is the winner.

Teacher notes

The biggest challenge with this task is working out how to make the robots signal each other. It’s always very interesting to see how teams solve this problem. Over the years I’ve seen students try all the sensors available in the EV3 sets, with varying levels of success.

As always, I encourage a diversity of solutions. For example, even though it’s typically quite difficult to solve this challenge using the touch sensor, I don’t discourage its use – after all, it provides a great lesson about the value of reliability and repeatability in robotic systems.


I use the following approach to score each team’s performance.

  • First robot
    • Starts on a touch sensor press (1 point)
    • Stops after crossing tape on opposite side (1 point)
  • Second robot
    • Starts autonomously when the first robot crosses the line (1 point)
    • Stops after crossing tape on opposite side (1 point)
  • Stretch goals for bonus points
    • Your robots are reliable – or you win the race! (1 point)
    • Your robots complete the race having passed a “baton” (1 point)
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Rob Torok

I'm a teacher in Tasmania, Australia, and have been using LEGO MINDSTORMS with my students since 2001. I'm the editor in chief for LEGO Engineering (this site) as well as the content editor for LEGO Education Australia (

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